Effect of water withdrawal on formation of free radical, proline accumulation and activities of antioxidant enzymes in ZAT12-transformed transgenic tomato plants

Water stress often leads to the accumulation of reactive oxygen species (ROS) and their excessive production alters the activities of enzymes involved in their removal. ZAT12 is a member of stress-responsive C2H2 type Zinc Finger Protein (ZFP) reported to control the expression of several stress-activated genes in plants through ROS signaling. The ZAT12-transformed tomato lines (cv. H-86 variety Kashi Vishesh) when subjected to water withdrawal for 7, 14 and 21 days revealed significant and consistent changes in activities of enzymes SOD, CAT, APX, GR and POD paralleled with an increased proline levels. Unlike that in wild-type tomato, the leaf superoxide anion and hydrogen peroxide concentrations in the transformed tomato plants did not alter much, suggesting a well regulated formation of free radicals suppressing oxidative stress in the latter. Results suggest BcZAT12-transformed tomato lines ZT1, ZT2 and ZT6 to be better adapted to drought stress tolerance by accumulation of osmolyte proline and increased antioxidant response triggered by the ZAT12 gene. Therefore, the ZAT12-transformed tomato cv. H-86 lines will prove useful for higher yield of tomato crop in regions affected with severe drought stress.

► ZAT12 (C2H2 Zn finger protein) transformed tomato had altered expression of SOD, CAT, APX, GR and POD. ► More accumulation of proline in transformants appeared. ► The level of O2− and H2O2 remained unaltered. ► A higher drought tolerance in tomato transformants ZT1, ZT2 and ZT6 is indicated. ► Drought tolerant tomato has applications for improved yield under drought conditions.